Berion
Developer
I tested both: MBR and GPT and I can confirm that both ARE fixable by partition table transplantation. At least on CECHL04 with OFW 3.55. 
For MBR You need 512B, for GPT 17KiB. It is unfixable only if user additionally create partition on such disk.
I didn't test device with larger than 512B sector size, so I don't know if PS3 aligning logic sector to physical size. If she doing it, then for MBR will be 4KiB and for GPT 136KiB.
Tutorial is in Polish, but can be blindly step by step based on images.
For MBR You need 512B, for GPT 17KiB. It is unfixable only if user additionally create partition on such disk.
I didn't test device with larger than 512B sector size, so I don't know if PS3 aligning logic sector to physical size. If she doing it, then for MBR will be 4KiB and for GPT 136KiB.
Tutorial is in Polish, but can be blindly step by step based on images.